A luminaire is generally understood to include one or more light producing subsystems carried by a housing along with power, driving, and/or power distribution devices. In this manner, the luminaire provides a single unit that is easy to install and/or ship. An example of a luminaire is a light fixture, such as a hanging light fixture commonly installed to hang from a ceiling or wall. However, there are many different types of luminaires, and the luminaires discussed herein are to be considered representative of all such devices.
Lighting installations for illuminating driving surfaces, such as road ways and parking lots, often utilize one or more luminaires for providing the desired illumination. Some basic concerns when so used is providing light at an angle that provides the desired illumination of the driving surface while at the same time minimizing or eliminating glare of direct light into the eyes of drivers. In order to accomplish this, it is customary to adjust the luminaires such that light emitted from a luminaire is focused along a particular focus pattern and/or angle to provide the desired illumination without being directed directly into the eyes of a driver driving a typical automobile on the driving surface.
The use of light emitting diode (LED) based lighting systems for luminaires is more and more commonplace due to their energy efficiency and life span. LEDs generate an intense point of light, which is generally anisotropic and has a narrow incident beam. The directionality of the light emitted by the LEDs can cause excessive and/or undesirable glare, which can make LEDs very bright and harsh to look at. As pointed out above, such glare can be of particular concern when used for lighting a driving surface. Thus, although desirable for efficiency, the use of LEDs for illuminating driving surfaces, and in particular streets and highways, could be problematic unless proper glare-reducing measures are taken.
An ideal design of an LED lighting system in a luminaire for driving surfaces provides sufficient illumination levels on the ground while creating the effect of minimal light at the LEDs. To help achieve this objective, many LED manufacturers place a primary optic (e.g., a lens) over the semi-conductor element of each LED to create a lambertian light distribution pattern. While this light distribution pattern reduces glare to some degree, roadway lighting often requires an even greater amount of glare reduction. In these cases, it is customary to place a secondary optic (e.g., a lens) over each of the LEDs (as well as the primary optic) to further focus and/or distribute the light in a desired manner. Additional measures, such as adding tertiary optics in the form of additional lenses and/or diffusers is also common, depending on the specific needs of the lighting installation. Adding the secondary optic, as opposed to simply modifying the primary optic, is preferred because the primary optic is typically installed by the manufacturer of the LED and is closely integrated with the semi-conductor element of the LED. The secondary optic, which is typically manufactured separately from the LED/primary optic element, can then be placed over the LED/primary optic relatively easily at a later time.
Typical secondary optics are manufactured by molding an optics material, such as glass or polycarbonate, into one or more secondary optics carried by a base. Molding is a relatively efficient way to manufacture the secondary optic, in particular when several separate optics are carried by a single base. In this manner, a secondary optic may be in the form of a panel having several individual optics carried by a base, wherein a single panel may be used to fix several individual optics over a corresponding number of individual LEDs (and the corresponding primary optics).
When manufactured by such molding methods, however, it may be difficult to mold the desired size and/or shape of the individual optics as a single, integral mass along with the base due to manufacturing constraints. Thus, it may not be possible to obtain the desired size and/or shape of the optics in such a molding operation, in particular where the optic has a relatively complex shape. However, the desired light focusing properties needed for reducing glare in the LED lighting systems for luminaires used for illuminating driving surfaces often have a relatively complex shape. Thus, it would be beneficial to have an optic panel that is both easy to manufacture by molding and provides the light focusing properties desired for illuminating driving surfaces.